On Wed, Sep 25, 2024 at 10:18 AM Jan Kara <jack@xxxxxxx> wrote:
>
> On Wed 25-09-24 10:11:46, Jan Kara wrote:
> > On Tue 24-09-24 12:07:51, Krishna Vivek Vitta wrote:
> > > Please ignore the last line.
> > > Git clone operation is failing with fanotify example code as well.
> > >
> > > root@MININT-S244RA7:/mnt/c/Users/kvitta/Desktop/MDE binaries/GitCloneIssue# ./fanotify_ex /mnt/c
> > > Press enter key to terminate.
> > > root@MININT-S244RA7:/mnt/c/Users/kvitta/Desktop/MDE binaries/GitCloneIssue# ./fanotify_ex /mnt/c
> > > Press enter key to terminate.
> > > Listening for events.
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/info/exclude
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/info/exclude
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/hooks/pre-applypatch.sample
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/hooks/pre-applypatch.sample
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/hooks/applypatch-msg.sample
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/hooks/applypatch-msg.sample
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/hooks/commit-msg.sample
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/hooks/commit-msg.sample
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/hooks/pre-push.sample
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/hooks/pre-push.sample
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/hooks/pre-merge-commit.sample
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/hooks/pre-merge-commit.sample
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/hooks/pre-commit.sample
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/hooks/pre-commit.sample
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/hooks/post-update.sample
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/hooks/post-update.sample
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/hooks/push-to-checkout.sample
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/hooks/push-to-checkout.sample
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/hooks/fsmonitor-watchman.sample
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/hooks/fsmonitor-watchman.sample
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/hooks/update.sample
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/hooks/update.sample
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/hooks/pre-rebase.sample
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/hooks/pre-rebase.sample
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/hooks/pre-receive.sample
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/hooks/pre-receive.sample
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/hooks/prepare-commit-msg.sample
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/hooks/prepare-commit-msg.sample
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/description
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/description
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/HEAD.lock
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/HEAD.lock
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/config.lock
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/config.lock
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/config.lock
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/config
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/config
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/config
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/config.lock
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/config
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/config
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/config
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/config.lock
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/config
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/config
> > > FAN_CLOSE_WRITE: File /mnt/c/Users/kvitta/gtest/.git/config
> > > FAN_OPEN_PERM: File /mnt/c/Users/kvitta/gtest/.git/tNbqjiA
> > > read: No such file or directory
> > > root@MININT-S244RA7:/mnt/c/Users/kvitta/Desktop/MDE binaries/GitCloneIssue#
> >
> > OK, so it appears that dentry_open() is failing with ENOENT when we try to
> > open the file descriptor to return with the event. This is indeed
> > unexpected from the filesystem.
How did you conclude that is what is happening?
Were you able to reproduce, because I did not.
> > On the other hand we already do silently
> > fixup similar EOPENSTALE error that can come from NFS so perhaps we should
> > be fixing ENOENT similarly? What do you thing Amir?
>
But we never return this error to the caller for a non-permission event,
so what am I missing?
> But what is still unclear to me is how this failure to generate fanotify
> event relates to git clone failing. Perhaps the dentry references fanotify
> holds in the notification queue confuse 9p and it returns those ENOENT
> errors?
My guess is that ENOENT for openat(2)/newfstatat(2) is from this code
in fid_out label in:
v9fs_vfs_getattr() => v9fs_fid_lookup() =>
v9fs_fid_lookup_with_uid()
if (d_unhashed(dentry)) {
spin_unlock(&dentry->d_lock);
p9_fid_put(fid);
fid = ERR_PTR(-ENOENT);
} else {
__add_fid(dentry, fid);
So fanotify contributes a deferred reference on the dentry,
and that can somehow lead to operating on a stale unhashed dentry?
Not exactly sure how to piece that all together.
This seems like a problem that requires p9 developers to look at it.
fanotify mark has an indirect effect on this use case IMO.
Thanks,
Amir.
